Processes for the production of such faujasite zeolites are well known (see for example, the X zeolite of Milton, U.S. Pat. No. 2,882,243, and the Y zeolite of Breck, U.S. Pat. No. 3,130,007) in which the source of the aluminum and silicon elements are soluble salts of the aluminum and silicon elements reported as SiO.sub.2 and Al.sub.2 O.sub.3. Instead of such soluble salts, clays are employed as a source of the Al.sub.2 O.sub.3 and SiO.sub.2 (see Howell, U.S. Pat. No. 3,119,600 and Secor, U.S. Pat. No. 3,446,727, and Secor, et al., U.S. Pat. No. 4,010,116). The literature relating to these processes is voluminous and the above listing is merely illustrative.
In all of these processes, the reaction mix which is required to form the zeolite contains a substantially higher ratio of Na.sub.2 O:Al.sub.2 O.sub.3 and SiO.sub.2 :Al.sub.2 O.sub.3 and H.sub.2 O:Al.sub.2 O.sub.3 than in the zeolite product produced. The slurry of zeolite produced is filtered, and the filter cake is washed.
For the purposes of economy, filtrate is used to form a new batch of zeolite. The filtrate is adjusted in composition to provide the ratio of the Na.sub.2 O/SiO.sub.2 :SiO.sub.2 /Al.sub.2 O.sub.3 :H.sub.2 O/Al.sub.2 O.sub.3 required in the reaction mix. This requires the addition of silica or alumina or aluminum and silicon salts or clay, depending upon the source of this SiO.sub.2 and Al.sub.2 O.sub.3 desired to reestablish the ratios of the reaction mix to produce the zeolite.
In the procedures, as set forth in the patents referred to above, and also used in commercial operations, the reaction mix is first digested at a relatively low temperature for a long period of time (the cold soak) and then heated to a higher temperature for an additional period of time (the hot soak). As set forth in Secor, et al., supra, open steam is used to heat the hot soak.
The low temperature period is an induction period during which amorphous nucleation centers develop and which then result in the generation of the crystallization phase in the hot soak. (See generally, Breck, "Zeolite Molecular Sieve", John Wiley & Sons, 1974, pp. 333, etc.)